The key political fact about the proposed Keystone XL tar sands oil pipeline from Canada to the Gulf of Mexico is this: at the end of the day, the decision of whether to approve the permit for the pipeline or not will be a political decision wholly owned by President Obama.
The final determination on the permit will be based whether approval would be in the "national interest" of the United States. This is an inherently political determination. By denying the permit for the pipeline, President Obama can take a concrete action against climate chaos without securing one Republican vote, without spending one tax dollar, without getting approval from the Tea Party.
If, on the other hand, President Obama were to approve the permit for the pipeline, then he would be acting to promote climate chaos, and this decision could not be blamed on the dispute over the nation's projected debt in 2021, Republicans or the Tea Party. It would be President Obama, standing alone, breaking a campaign promise to act to protect the climate from chaos induced by human action.
This is a global justice issue, because climate chaos is inherently discriminatory against the poor and the weak. A hurricane that strikes Haiti and Florida with the same force is virtually guaranteed to hurt Haitians more, because Haiti has fewer resources to protect its citizens against hurricanes. More Haitians have inadequate shelter to start with; the infrastructure for emergency response is weaker; the health care system is weaker. So any action which has the effect of making hurricanes more intense is going to have disparate impact on Florida and Haiti, for the future as far as we can see.
The Intergovernmental Panel on Climate Change has noted: